1. Field of the Invention
The present invention relates to an electrochemical device using solid polymer electrolytic film based on an electrochemical reaction. In particular, the present invention relates to an electrochemical device which generates gases such as an ozone gas, an oxygen gas and a hydrogen gas by an electrochemical reaction in the process of inducing direct current voltage by facing an anode with a cathode having a solid polymer electrolytic film therebetween. The present invention also relates to an electrochemical device such as a dehumidifying device which dehumidifies moisture in air, or a gas detection sensor which detects a leaked gas.
2. Description of the Related Art
Prior Art Embodiment 1
FIG. 42 shows a constructional view of a dehumidifying device which is an example of the conventional electrochemical device using a solid electrolytic film disclosed, for example, in Japanese Unexamined Patent Publication No. 216714/1986. In the figure, numeral 101 indicates an anode, numeral 102 a cathode, numeral 103 a solid polymer electrolytic film, numeral 105 a collector, numeral 106 and 107 a terminal plate, numeral 108 a case, numeral 109 a pump, numeral 110 a cathode room, numeral 111 an anode room, numeral 112 a water pool, numeral 113 an exhaust port for remaining gas and numeral 114 an oxygen exhaust port.
Anode 101 and cathode 102 are jointed to each surface of a solid polymer electrolytic film 103 comprising perfluorocarbon sulfonate resin as a whole. The anode 101 comprises platinum and is jointed to solid polymer electrolytic film 103 by non-electrolytic plating. The cathode 102 is constituted by jointing a composition comprising carbon powder having platinum catalyst, poly(tetra-fluoroethylene), perfluorocarbon sulfonic acid resin and the like to solid polymer electrolytic film 103 by a hot press method. Wave-shaped collectors 104 and 105 are placed behind anode 101 and cathode 102, respectively. Further, titanium terminal plates 106 and 107 are placed behind the collectors 104 and 105, respectively. These elements are fixed by a case 108. Additionally, air for dehumidification is introduced by a pump 109 into cathode room 110 and anode room 111 which are formed in each space around anode collector 104 and cathode collector 105, respectively.
Water vapor in the introduced air is absorbed by solid polymer electrolytic film 103. If a direct current voltage of 1.4 V is induced between the cathode terminal plate 106 and the anode terminal plate 107 in this condition, electrolytic reductive reaction of oxygen is observed at the cathode 102, while oxygen is generated at the anode 101, leading to leakage of water from the back of the cathode 102. The leaked water is pooled in water pool 112 and the remaining gas deoxidated at the cathode 102 is released into air through the remaining gas exhaust port 113 set on the water pool 112. Also, oxygen generated from the anode 101 is released into air through oxygen exhaust port 114 together with redundant air. In this manner, water vapor in air is condensed and is collected in the water pool 112 in liquid condition.
However, a dehumidifying device according to Prior art Embodiment 1 had a problem in that the electrochemical device became heavy and thick since solid polymer electrolytic film 103 is contacted to the anode 101 and the cathode 102 with surface pressure by inserting the solid polymer electrolytic film 103 jointed with the anode 101 and the cathode 102 sandwiched by the collectors 104 and 105 and the terminal plates 106 and 107 into the case 108.
Prior Art Embodiment 2
In order to solve the above problems, there is provided a dehumidifying device which is an example of the conventional electrochemical device using a solid electrolytic film as disclosed for example in Japanese Unexamined Patent Publication Nos. 325983/1993 and 63343/1994, in which a solid polymer electrolytic film with an anode and a cathode is closely contacted to each other without the collectors 104 and 105, the terminal plates 106 and 107 or the case 108. Also, an ozone generating device is proposed which is an example of the conventional electrochemical device using a solid electrolytic film as disclosed in Japanese Unexamined Patent Publication No. 131276/1999.
In these electrochemical devices, on either side of a solid polymer electrolytic film, there are placed an anode having an anode catalytic layer on an anode base substrate comprising conductive porous material and a cathode having an cathode catalytic layer on cathode base substrate comprising conductive porous material. Thermocompression bonding (hot press) is carried out at a temperature of at least 130xc2x0 C. to less than 210xc2x0 C. so as to insert the anode and cathode base substrate into a solid polymer electrolytic film. A catalytic layer is formed in the inserted part to achieve close contact.
For example, FIG. 43 shows a construction view of an ozone generator disclosed in Japanese Unexamined Patent Publication No. 131276/1999, being an example of the conventional electrochemical device using a solid electrolytic film. An electrochemical device is formed by hot press at 160xc2x0 C. placing, on both surfaces of a solid electrolytic film, an anode 1 having an anode catalytic layer on an anode base substrate comprising conductive porous material and a cathode 2 having an cathode catalytic layer on a cathode base substrate comprising conductive porous material.
When about 3 V of direct current voltage by using current power 6 is induced to the electrochemical device formed in unity, water in air is electrolyzed at the jointed surface of the anode 1 and solid polymer electrolytic film 3 to generate an ozone gas, an oxygen gas and electrons. The generated ozone gas and oxygen gas are released outside through the anode 1 which is a porous material. On the other hand, the hydrogen ions generated by electrolysis of water move to the cathode 2 through the solid polymer electrolytic film 3 and water is generated at the jointed surface of the cathode 2 and the solid polymer electrolytic film 3 by reacting the hydrogen ions, oxygen gas in air and electrons led to the cathode 2 from the outside circuit.
The electrochemical device of the Prior art Embodiment 2 using a solid electrolytic film has an advantage of omitting the collectors 104 and 105, the terminal plates 106 and 107 and the case 108, leading to a light and thin solid electrolytic film since the anode 1, the cathode 2 and the solid electrolytic film 3 are unified as a whole by using hot press.
However, there was a problem in that performance of the electrochemical device of Prior art Embodiment 2 decreases in a short period of time if it is used at a high humidity condition wherein relative humidity is more than 70%.
The present invention has been conducted to solve the problems with the above conventional devices, and the object of the present invention is to provide an electrochemical device comprising a thin and light solid polymer electrolytic film whose properties can be maintained steadily for a long time even at a high humidity condition and a process for preparing the same.
The first electrochemical device of the present invention is obtained by inserting and pressuring a jointed electrochemical device between a pair of pressing plates, wherein the jointed electrochemical device is obtained by jointing an anode and a cathode having a catalytic layer on a base substrate of conductive porous material to both sides of the solid polymer electrolytic film, and wherein the pressing plate has an opening part having an area smaller than an electrochemical reaction part formed by facing the anode and the cathode.
The second electrochemical device of the present invention is a device in which an area of the opening part is 5 to 90% to an area of the electrochemical reaction part in the first device.
The third electrochemical device of the present invention is a device in which the opening part is a plurality of through holes formed on the pressing plate in the first device.
The forth electrochemical device of the present invention is a device in which the pressing plate comprises a metal plate and an insulating resin sheet present between the metal plate and an anode or a cathode, or an insulating resin film covering the metal plate in the first device.
The fifth electrochemical device of the present invention is a device in which the pressing plate comprises an insulating resin plate or an insulating ceramics plate in the first device.
The sixth electrochemical device of the present invention is a device in which the pressing plate is jointed with the device by an insulating adhesive agent except for at least the above opening part in the first device.
The seventh electrochemical device of the present invention is a device in which the opening part is a plurality of through holes formed on the pressing plate in the sixth device.
The eighth electrochemical device of the present invention is a device in which the pressing plate comprises a metal plate and an insulating resin film covering the metal plate in the sixth device.
The ninth electrochemical device of the present invention is a device in which the pressing plate comprises an insulating resin film or an insulating ceramics plate in the sixth device.
The tenth electrochemical device of the present invention is a device in which at least one of the pressing plates has a concave part to which the above jointed electrochemical device is inserted in the first device.
The eleventh electrochemical device of the present invention is a device in which the opening part is a plurality of through holes on a pressing plate in the tenth device.
The twelfth electrochemical device of the present invention is a device in which the pressing plate comprises a metal plate and an insulating resin film covering the metal plate in the tenth device.
The thirteenth electrochemical device of the present invention is a device in which the pressing plate comprises an insulating resin film or an insulating ceramics plate in the tenth device.
The fourteenth electrochemical device of the present invention is a device in which the pressing plate is jointed with the device by an insulating adhesive agent except for at least the above opening part in the tenth device.
The fifteenth electrochemical device of the present invention is a device which has an opening part to which the jointed electrochemical device is inserted, and wherein spacers thinner than the jointed electrochemical device are placed between a pair of pressing plates in the first device.
The sixteenth electrochemical device of the present invention is a device in which the pressing plate comprises an insulating resin plate or an insulating ceramics plate in the fifteenth device.
The seventeenth electrochemical device of the present invention is a device in which the pressing plate is jointed by an insulating adhesive agent except for at least the opening part in the fifteenth device.
The air conditioner of the present invention is an air conditioner comprising the electrochemical device of the first electrochemical device.
The refrigerator of the present invention is an air conditioner comprising the electrochemical device of the first electrochemical device.
The process for preparing the first electrochemical device of the present invention is a process for preparing an electrochemical device comprising a jointed electrochemical device, which is obtained by jointing an anode and a cathode having a catalytic layer on a base substrate of conductive porous material to both sides of a solid polymer electrolytic film, and a pair of pressing plates, which is placed to insert the electrochemical device between the anode and cathode side and has an opening part corresponding to an electrochemical reaction part formed by facing the anode and cathode, wherein the pressing plate is placed on the anode and cathode side of the jointed electrochemical device by using a sheet of insulating adhesive agent therebetween and hot-pressed to joint the pressing plate.